The present invention generally relates to magnetic disks, magnetic recording and reproducing methods and magnetic disk units, and more particularly to a magnetic disk, a magnetic recording and reproducing apparatus and a magnetic disk unit which magnetically record and reproduce signals with a high density.
Recently, the recording density of the magnetic disk has increased considerably. There are several reasons for the increased recording density of the magnetic disk, and the realization of a magneto-resistance effect type head (hereinafter simply referred to as a MR head) using a magneto-resistance element is one of the reasons for the increased recording density. The MR head can detect with a high sensitivity the magnetization states recorded on the magnetic disk, thereby making it possible to magnetically record and reproduce signals with a high density.
The MR head can only reproduce the signals recorded on the magnetic disk, and thus, the signals are usually recorded on the magnetic disk using a thin film head. For this reason, the magnetic disk unit is provided with a write head for recording the signals and a read head for reproducing the signals.
The write head and the read head are provided on an actuator which moves these heads generally in a radial direction of the magnetic disk. But although the write head and the read head are provided close together as much as possible, these heads are inevitably separated by a predetermined distance in a direction approximately perpendicular to the radial direction of the magnetic disk.
In addition, due to the demands to reduce the size of the magnetic disk unit or the like, the actuator is in most cases turned rather than being moved linearly. When the actuator is turned, an angle formed by each head and a track on the magnetic disk becomes different depending on the position of each head. For example, an azimuth angle is different at an inner peripheral portion of the magnetic disk and an outer peripheral portion of the magnetic disk. As a result, each head deviates in opposite directions with respect to the track at the inner peripheral portion of the magnetic disk and at the outer peripheral portion of the magnetic disk.
If the read head deviates with respect to a target track at the time of reproducing the signals due to the azimuth angle described above, the read head can only scan a portion of the target track. In addition, the read head also scans a portion of a track which is adjacent to the target track which is to be scanned, thereby mixing noise into the reproduced signals. Consequently, the read head cannot reproduce the signals recorded on the magnetic disk in a satisfactory manner. For this reason, a so-called wide-write/narrow-read is carried out, wherein the signals are recorded on the magnetic disk by a wide write head and the recorded signals are reproduced from the magnetic disk by a narrow read head. In the case of the wide-write/narrow-read, the signals are recorded on the magnetic disk by the wide write head which is wider than the narrow read head. As a result, even if the narrow read head deviates with respect to the target track due to the azimuth angle, the narrow read head only scans the target track which is to be scanned, and the signal-to-noise (S/N) ratio of the reproduced signal is improved.
However, when the wide-write/narrow-read is employed, the S/N ratio of the reproduced signals is improved because the signals are recorded using the wide write head, but there was a problem in that the recording density of the magnetic disk becomes poor. In other words, employing the wide-write/narrow-read described above did not agree with the object of using the MR head as the read head in order to realize the high density recording and reproduction.
On the other hand, the track pitch wave conventionally set constant for the entire recording region of the magnetic disk. The track pitch is determined by a sum of the width of the write head and the width of a dead space which is required in order to reduce the crosstalk from the adjacent track. Accordingly, in order to prevent the undesirable effects of the crosstalk from the adjacent track, it was not possible to greatly reduce the track pitch. In other words, there was another problem in that it is impossible to greatly improve the recording density of the magnetic disk without deteriorating the S/N ratio of the reproduced signals.
Accordingly, it is a general object of the present invention to provide a novel and useful magnetic disk, magnetic recording and reproducing apparatus and magnetic disk unit, in which the problems described above are eliminated.
Another and more specific object of the present invention is to provide a magnetic disk, magnetic recording and reproducing apparatus and magnetic disk unit, which can improve the recording density of the magnetic disk without deteriorating the S/N ratio of the reproduced signals.
Still another object of the present invention is to provide a magnetic disk on which signals are recorded on and reproduced from a head with an azimuth angle which changes depending on a radial position on the magnetic disk, the magnetic disk comprising a first recording region having tracks recorded with an azimuth angle less than or equal to a predetermined value, a second recording region having tracks recorded with an azimuth angle greater than the predetermined value, and an overlapping region in which two mutually adjacent tracks overlap in a radial direction of the magnetic disk, where a track pitch of the tracks within the first recording region is different from a track pitch of the tracks within the second recording region. According to the magnetic disk of the present invention, it is possible to improve the S/N ratio of the reproduced signals and improve the data reliability, and further, it is possible to realize a high-density recording and reproduction.
Another object of the present invention is to provide a magnetic recording and reproducing method for recording signals on and reproducing signals from a magnetic disk by a head having an azimuth angle which changes depending on a radial position on the magnetic disk, the magnetic recording and reproducing method comprising the steps of (a) recording signals on tracks having a first track pitch with an azimuth angle less than or equal to a predetermined value with respect to a first recording region of the magnetic disk, and recording signals on tracks having a second track pitch which is different from the first track pitch with an azimuth angle greater than the predetermined value with respect to a second recording region of the magnetic disk, the first recording region being different from the second recording region, and (b) reproducing signals from the first recording region with the azimuth angle less than equal to the predetermined value, and reproducing signals from the second recording region with the azimuth angle greater than the predetermined value, the step (a) recording the signals on each of the tracks so that two mutually adjacent tracks overlap in a radial direction of the magnetic disk within an overlapping region located in at least a part of the first recording region. According to the magnetic recording and reproducing method of the present invention, it is possible to improve the S/N ratio of the reproduced signals and improve the data reliability, and further, it is possible to realize a high-density recording and reproduction.
Another object of the present invention is to provide a magnetic recording and reproducing method for recording signals on and reproducing signals from a magnetic disk by a head having an azimuth angle which changes depending on a radial position on the magnetic disk, the magnetic recording and reproducing method comprising the steps of (a) recording signals on tracks having a first track pitch with an azimuth angle less than or equal to a predetermined value with respect to a first recording region of the magnetic disk, and recording signals on tracks having a second track pitch which is different from the first track pitch with an azimuth angle greater than the predetermined value with respect to a second recording region of the magnetic disk, the first recording region being different from the second recording region, and (b) reproducing signals from the first recording region with the azimuth angle less than equal to the predetermined value, and reproducing signals from the second recording region with the azimuth angle greater than the predetermined value, where the step (b) uses a read head having a center which is offset generally in a radial direction of the magnetic disk with respect to a center of a write head used by the step (a). According to the magnetic recording and reproducing method of the present invention, it is possible to realize a high-density recording and reproduction without deteriorating the S/N ratio of the reproduced signals.
Still another object of the present invention is to provide a magnetic recording and reproducing method for recording signals on and reproducing signals from a magnetic disk by a head having an azimuth angle which changes depending on a radial position on the magnetic disk, the magnetic recording and reproducing method comprising the steps of (a) recording signals on tracks having a first track pitch with an azimuth angle less than or equal to a predetermined value with respect to a first recording region of the magnetic disk, and recording signals on tracks having a second track pitch which is smaller than the first track pitch with an azimuth angle greater than the predetermined value with respect to a second recording region of the magnetic disk, the first recording region being different from the second recording region, and (b) reproducing signals from the first recording region with the azimuth angle less than equal to the predetermined value, and reproducing signals from the second recording region with the azimuth angle greater than the predetermined value. According to the magnetic recording and reproducing method of the present invention, it is possible to realize a high-density recording and reproduction without deteriorating the S/N ratio of the reproduced signals.
A further object of the present invention is to provide a magnetic disk unit for recording signals on and reproducing signals from a magnetic disk using a head having an azimuth angle which changes depending on a radial position on the magnetic disk, comprising a write head recording signals on tracks of the magnetic disk, a read head reproducing signals from the tracks, a moving mechanism moving the write head and the read head generally in a radial direction of the magnetic disk in a state where the write head and the read head are separated in a direction approximately perpendicular to the radial direction of the magnetic disk, and control means for controlling an amount the write head and the read head are moved by the moving mechanism, where the control means controls the moving mechanism so that the write head records signals on tracks having a first track pitch with an azimuth angle less than or equal to a predetermined value with respect to a first recording region of the magnetic disk, and records signals on tracks having a second track pitch which is different from the first track pitch with an azimuth angle greater than the predetermined value with respect to a second recording region of the magnetic disk, so that two mutually adjacent tracks overlap in the radial direction of the magnetic disk within an overlapping region located in at least a part of the first recording region, the first recording region being different from the second recording region, and the control means controls the moving mechanism so that the read head reproduces signals from the first recording region with the azimuth angle less than equal to the predetermined value, and reproduces signals from the second recording region with the azimuth angle greater than the predetermined value. According to the magnetic disk unit of the present invention, According to the magnetic disk unit of the present invention, it is possible to improve the S/N ratio of the reproduced signals and improve the data reliability, and further, it is possible to realize a high-density recording and reproduction.
Another object of the present invention is to provide a magnetic disk unit for recording signals on and reproducing signals from a magnetic disk using a head having an azimuth angle which changes depending on a radial position on the magnetic disk, comprising a write head recording signals on tracks of the magnetic disk, a read head reproducing signals from the tracks, a moving mechanism moving the write head and the read head generally in a radial direction of the magnetic disk in a state where the write head and the read head are separated in a direction approximately perpendicular to the radial direction of the magnetic disk, and control means for controlling an amount the write head and the read head are moved by the moving mechanism, where the control means controls the moving mechanism so that the write head records signals on tracks having a first track pitch with an azimuth angle less than or equal to a predetermined value with respect to a first recording region of the magnetic disk, and records signals on tracks having a second track pitch which is different from the first track pitch with an azimuth angle greater than the predetermined value with respect to a second recording region of the magnetic disk, so that two mutually adjacent tracks overlap in the radial direction of the magnetic disk within an overlapping region located in at least a part of the first recording region, the first recording region being different from the second recording region, the control means controls the moving mechanism so that the read head reproduces signals from the first recording region with the azimuth angle less than equal to the predetermined value, and reproduces signals from the second recording region with the azimuth angle greater than the predetermined value, and the read head has a center which is offset generally in the radial direction of the magnetic disk with respect to a center of the write head. According to the magnetic disk unit of the present invention, it is possible to realize a high-density recording and reproduction without deteriorating the S/N ratio of the reproduced signals.
Still another object of the present invention is to provide a magnetic disk unit for recording signals on and reproducing signals from a magnetic disk using a head having an azimuth angle which changes depending on a radial position on the magnetic disk, comprising a write head recording signals on tracks of the magnetic disk, a read head reproducing signals from the tracks, a moving mechanism moving the write head and the read head generally in a radial direction of the magnetic disk in a state where the write head and the read head are separated in a direction approximately perpendicular to the radial direction of the magnetic disk, and control means for controlling an amount the write head and the read head are moved by the moving mechanism, where the control means controls the moving mechanism so that the write head records signals on tracks having a first track pitch with an azimuth angle less than or equal to a predetermined value with respect to a first recording region of the magnetic disk, and records signals on tracks having a second track pitch which is smaller than the first track pitch with an azimuth angle greater than the predetermined value with respect to a second recording region of the magnetic disk, the first recording region being different from the second recording region, and the control means controls the moving mechanism so that the read head reproduces signals from the first recording region with the azimuth angle less than equal to the predetermined value, and reproduces signals from the second recording region with the azimuth angle greater than the :predetermined value. According to the magnetic disk unit of the present invention, it is possible to realize a high-density recording and reproduction without deteriorating the S/N ratio of the reproduced signals.